In recent years, avionics engineers have endeavored to enhance the economy and safety of aircraft operations. One example is the recent use of global positioning system (GPS) receivers and Flight Management Systems (FMS) to provide enhanced navigation guidance, with greater accuracy and less reliance on ground based navigational aids. Typically in such systems the information from the FMS is switched into the stream of information normally extending from a Distance Measuring Equipment (DME) interrogator to the instruments which display distance to a station to the pilot and any automatic flight control system.
While this approach does have several beneficial aspects, it has several shortcomings. First of all, it requires severing of the aircraft wiring between the DME interrogator and the instruments. The integrity of these wires is essential to safety of flight in some aircraft. Consequently, any alterations of these wires is regulated by the Federal Aviation Administration (FAA). Secondly, an expensive and/or failure prone electro-mechanical switching device is required. Thirdly, the FMS must have multiple types of distance signals to match the various generations and technologies of aircraft.
Consequently, there exists a need for an improved system for integrating an additional navigation system into an existing aircraft design.